Are you using LXDE?

[Alan Cox]

On Tue, 02 Jun 2009 13:21:36 +0200
Kevin Kofler <kevin.kofler at chello.at> wrote:

> John Aldrich wrote:
> > I don't know why KDE is so slow on my machine
> 
> Well...
> 
> > NVidia graphics card
> 
> ... that's why. Crap drivers.

Nouveau accelerates 2D and render for most stuff so even if using the
open source drivers that shouldn't be a material problem unless you have
all the wacky compositing wobbly window desktop effects enabled.

Definitely worth seeing if switching to the nouveau drivers helps if your
machine has for some reason default to nv.

If not then its worth more investigation

Alan